[TASK] Add performance benchmark infrastructure

Add benchmark scripts for measuring render performance:
- benchmark/run-benchmark.sh: Cold/warm/partial scenarios
- benchmark/compare-branches.sh: Branch comparison
- Makefile targets: benchmark-cold, benchmark-warm, etc.

Uses Documentation-rendertest (94 RST files) as test project.

[TASK] Add Docker benchmark targets and gitignore for test docs

- Add Makefile targets for Docker-based benchmarks (reproducible)
- Ignore downloaded benchmark test documentation

[TASK] Add TYPO3 Core Changelog benchmark support

Add extra-large documentation benchmark (3666 files) for more
comprehensive performance testing.

Changes:
- Update download-test-docs.sh for sparse checkout from TYPO3 monorepo
- Add changelog docs type to benchmark-docker.sh
- Update HTML report with changelog results (95% faster: 997s -> 47s)
- Add changelog to all comparison tables and bar chart
- Update reproduction instructions with changelog commands

[TASK] Add real CPU/memory metrics to benchmarks

- Fix bar chart height to prevent overflow with changelog bar
- Install GNU time in Docker image for accurate metrics
- Run /usr/bin/time -v inside container (not outside)
- Capture wall time, CPU time, CPU%, and peak memory
- Update JSON output with extended metrics structure

Now reports actual PHP process metrics instead of estimates.
Example: 5.18s wall, 10.48s CPU (202%), 119.8MB memory

feat: Enhance benchmark infrastructure with profiling and parallelism matrix

Changes to benchmark-docker.sh:
- Use GUIDES_PROFILING=1 for accurate memory metrics via memory_get_peak_usage()
- Add 4th parameter for parallel mode: sequential, auto, or number (e.g., 16)
- Include parallel_mode in result filenames and JSON output
- Memory now sourced from PHP profiling instead of /usr/bin/time

New benchmark-main.sh:
- Dedicated script for benchmarking main branch with official container
- Uses ghcr.io/typo3-documentation/render-guides:latest
- Memory via /usr/bin/time (PHP profiling not available in official image)

New run-full-matrix.sh:
- Runs complete benchmark matrix:
  * main branch (official container)
  * feature branch: sequential (--parallel-workers=-1)
  * feature branch: auto (--parallel-workers=0)
  * feature branch: 16 workers (--parallel-workers=16)
- Supports small, large, changelog, or 'all' doc types

Usage examples:
  ./benchmark/benchmark-docker.sh cold 3 large sequential
  ./benchmark/benchmark-docker.sh cold 3 large auto
  ./benchmark/benchmark-docker.sh cold 3 large 16
  ./benchmark/run-full-matrix.sh large

Author: CybotTM

.gitignore

@@ -8,3 +8,7 @@
 /.phpdoc/
 /phpdoc.dist.xml
 *-temp/
+
+# Benchmark test documentation (downloaded on demand)
+/benchmark/test-docs/
+!/benchmark/test-docs/.gitkeep

Dockerfile

@@ -36,6 +36,8 @@ COPY --from=ghcr.io/php/pie:bin /pie /usr/bin/pie
 RUN apk add --update $PHPIZE_DEPS
 RUN pie install arnaud-lb/inotify && docker-php-ext-install pcntl
 
+# Install GNU time for benchmarking (busybox time doesn't support -v)
+RUN apk add --no-cache time
 RUN apk del $PHPIZE_DEPS && rm -rf /var/cache/apk/* /tmp/* /usr/share/php/* /usr/local/lib/php/doc/* /usr/local/lib/php/test/*
 
 COPY . /opt/guides

Makefile

@@ -217,3 +217,58 @@ vendor: composer.json composer.lock
 	@echo "$(ENV_INFO)"
 	$(PHP_COMPOSER_BIN) validate --no-check-publish
 	$(PHP_COMPOSER_BIN) install --no-interaction --no-progress --ignore-platform-reqs
+
+## LIST: Benchmark targets for performance testing
+
+.PHONY: benchmark-cold
+benchmark-cold: ## Run cold render benchmark (no cache)
+	@echo "$(ENV_INFO)"
+	./benchmark/run-benchmark.sh cold 3
+
+.PHONY: benchmark-warm
+benchmark-warm: ## Run warm render benchmark (with cache, no changes)
+	@echo "$(ENV_INFO)"
+	./benchmark/run-benchmark.sh warm 3
+
+.PHONY: benchmark-partial
+benchmark-partial: ## Run partial change benchmark (one file modified)
+	@echo "$(ENV_INFO)"
+	./benchmark/run-benchmark.sh partial 3
+
+.PHONY: benchmark-all
+benchmark-all: benchmark-cold benchmark-warm benchmark-partial ## Run all benchmark scenarios
+
+.PHONY: benchmark-compare
+benchmark-compare: ## Compare benchmarks between main and current branch
+	@echo "$(ENV_INFO)"
+	./benchmark/compare-branches.sh main
+
+## LIST: Docker-based benchmark targets (recommended for reproducibility)
+
+.PHONY: benchmark-download-docs
+benchmark-download-docs: ## Download TYPO3 CoreApi documentation for large benchmarks
+	./benchmark/download-test-docs.sh TYPO3CMS-Reference-CoreApi
+
+.PHONY: benchmark-docker-cold
+benchmark-docker-cold: docker-build ## Run cold benchmark in Docker (small docs)
+	./benchmark/benchmark-docker.sh cold 3 small
+
+.PHONY: benchmark-docker-warm
+benchmark-docker-warm: docker-build ## Run warm benchmark in Docker (small docs)
+	./benchmark/benchmark-docker.sh warm 3 small
+
+.PHONY: benchmark-docker-partial
+benchmark-docker-partial: docker-build ## Run partial benchmark in Docker (small docs)
+	./benchmark/benchmark-docker.sh partial 3 small
+
+.PHONY: benchmark-docker-all
+benchmark-docker-all: docker-build ## Run all benchmarks in Docker (small docs)
+	./benchmark/benchmark-docker.sh all 3 small
+
+.PHONY: benchmark-docker-large
+benchmark-docker-large: docker-build benchmark-download-docs ## Run all benchmarks with large TYPO3 docs
+	./benchmark/benchmark-docker.sh all 3 large
+
+.PHONY: benchmark-report
+benchmark-report: ## Generate markdown comparison report
+	./benchmark/generate-report.sh